Rotary compressor



June 17, 1947.

F. B. HALFQRD nounr courREsson I N LY Inventor June 17, 1947. F. B. HALFORD 3 2,422,615

ROTARY cournnsson Filed July 20, 1943 2 Sheets-Sheet 2 1 I T v v I v I k Inventor v am/ 4- duvmd 16%;!

- gfmm A tlorney Patented Jl me 17, 1947 ROTARY COMPRESSOR ,FrankBernard Halford. Edgware; England, as-

signor to The De Havilland Aircraft Company Limited, Edgware, England, a British company Application July 20, 1943, Serial No. 495,519

In Great Britain November 21, 1941 Section 1, Public Law 690, August 8, 19 16.

Patent expires November 21, 1961 v 1 Claim. 1

This invention relates to rotary compressors both of the single and double entry type and has for its object to provide a construction of impeller more especially intended for use with air or other gas and by which the fluid acted on is caused to flow radially at least in the impeller. The construction is more especially intended for the delivery of air into a chamber where fuel is burnt and whence the hot gases pass to act on a turbine by means of which the impeller is driven. The improved impeller may however be used in a compressor employed for other purposes.

According to this invention the blades of the impeller are formed by machining Without any bending from a'stamping "or forging, each blade throughout its Width in the axial direction being connected to and thus springing from a boss,

which is smoothly flared to a disc, and comprising a delivery portion which is substantially flat and where it is attached at one edge to this disc lies in a plane which contains and is thus'radial with respect to the impeller axis, the leading part of each blade having a helical form from its inlet edge to its junction with the flat delivery part, the section of each blade as it appears in any plane normal to the impeller axis being radial with respect to that axis. In such a construction the blades have a desirable strength and suitable shape which is due to each blade being given its final form in the machining process and thus without any bending. Throughout its whole width in the axialdirection the blade is integral with the boss the line of junction appearing curved on the boss in the longitudinal direction. Since the fluid dealt with passes radially over the delivery part of the blades with no axial component of flow, the tip of the delivery part of each blade follows a line which is parallel to the axis of the impeller and at right angles to the disc which forms the delivery end of the boss. As seen in an end view of the impeller, the ratio of the overall diameter of the blade tips at the inlet-to the overall diameter of the blade tips at the outlet is of the order of from .5 to .75 and preferably about .65. This propora 2 Figure 4 is a, transverse sectionthrough the impeller on the line 4-4 in Figure 3, that is in a plane normal to the impeller axis.

The boss A of the impeller is flared smoothly from its leading end A to a disc A and to this boss each blade B is attached along a line which at the leading part of the blade is curved as at C, as seen in Figure l, but becomes straight and lies radially as at 0 This can also be seen in the section shown in Figure 4. The blade and boss are integral the blade being formed by machining from a stamping or forging. The leading part B of each blade has ahelicabcurvature, but its delivery end portion B is flat as appears in the front view seen in Figure 1 and also in the section Figure 4. This delivery part lies radially with respect to the axis of the impeller. Any transverse section through a blade in a plane normal to the axis of the impeller will show the centre line of the blade at that place as lying radially with respect to that axis. This can be seen in the section shown in Figure 4 and other parallel sections would appear similarly and in' Figure 1 it will be seen that the leading edges B of the blades are straight and radial. The tip of each blade is a smooth curve as the overall tion in the measurements of these parts may vary in accordance with requirements.

The accompanying drawings illustrate by way of example a, construction of a single-entry im- .peller in which the present improvements are embodied. In these drawings:

Figure 1 is a front elevation of the impeller. Figure 2 is a side view thereof.

diameter of the blade increases in successive planes normal to the impeller axis. A fillet may be formed at the juncture between the blade and the boss and end disc. A taken in conjunction with the curvature of the leading-part B of the blade ensures a smooth transition of the fluid flow .in the impeller from the axial direction at the intake to the radial delivery at the outlet.

, As arranged for driving by a gas-driven tun. bine the-impeller may be coupled either directly or through gearing to that turbine which is driven by the gases delivered by the impeller after fuel has'been burnt in these gases.

- .In the case of a double-entry impeller the construction according to this invention will be the same except that the blades will be formed similarly on each side of the disc A which will then lie centrally.

The contour of the boss What I claim as my invention and desire to secure by Letters Patent is; a

An impeller for a compressor giving an essentially radial flow, said impeller having a hub which comprises a boss at the entering end that is smoothly flared to, a disk at the delivery end and a plurality of blades carried thereby,each of said blades having a substantially flat delivery portion which lies in a plane containing and thus radial with the impeller axis and a leading portion smoothly continuous throughout and integral with the delivery portion and 'having a helical form from its leading edge to its junction with said fiat portion so that any section of said leading portion in a plane normal to the impeller axis is truly radial with respect to said axis, each of said blades including its helical portion springing throughout its width in the 4 v axial direction from said boss and disk and hem I formed integrally therewith and each blade hav at the eye of the impeller a radial measurement not exceeding J75 of the radial measurement at .the delivery end of the blade.

. FRANK BERNARD HALFORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Garve' Nov. 4, 1941 

